A Southwest Airlines employee turned himself in to police last month and confessed to reissuing about $203,000 worth of airline gift cards to himself.

Christopher Olivas, 43, began unfreezing cards and reissuing the PIN numbers onto new gift cards in January 2013, according to the arrest warrant affidavit. He continued doing so until April 2014.

In September 2013, he was transferred from the customer relations office to the finance department where his job was detecting and investigating fraud. He had access to all the gift cards that had funds frozen on them.

He used some of the 457 gift cards to buy flights for friends and sold some on gift card trading sites, the affidavit states.

Southwest opened an internal investigation in April after a coworker noticed inconsistencies in one of Olivas' transactions.

Olivas turned himself in to Dallas police on May 21 and confessed to stealing the cards, using them for himself and selling them, the affidavit states. He was charged with theft and posted bail Monday night.

Southwest spokeswoman Whitney Eichinger said the airline is "fully cooperating" with Dallas police on the investigation.

Olivas was hired in February 2011. Eichinger could not say whether he still works for the airline.